The present invention relates to footwear and, more particularly, to a footwear sole construction and method for making the same.
There is an ongoing effort in the footwear industry to produce footwear that provides durability and flexibility. Many conventional footwear constructions, however, provide either comfort or flexibility—but usually not both—because the features providing these characteristics typically negate one another.
For example, one construction that is known for its flexibility is a direct attach construction, which includes an upper direct attached to an upper with a midsole. A typical direct attach construction includes a flat wearing outsole direct attached to a flexible polyurethane midsole, which in turn, is direct attached to an upper. The wearing outsole typically includes a flat upper surface to which the polyurethane midsole is secured by molding the polyurethane over the surface during manufacture of the shoe.
Although this direct attach construction is flexible and resilient, it is not sufficiently durable because the wearing outsole is prone to detach from the midsole, particularly in the toe region if a wearer scuffs their forefoot along the ground as they walk. In some cases, the outsole can detach completely from the midsole, which can cause injury to the wearer, especially if they are engaged in strenuous activity.
One solution to the detachment of the outsole from the midsole utilizes an outsole shell that encapsulates a lower part of the midsole. Such a construction is disclosed in U.S. Patent Application 2004/0143995 to McClelland, which is hereby incorporated by reference. In McClelland, the outsole shell includes wall that extends around the entire upper, from heel to toe. This wall includes inwardly extending scallops to which the midsole material direct attaches to form a mechanical interlock, which secures the outsole to the midsole. A potential issue with this durable construction, however, is that the midsole shell, and particularly the interlock, can sometimes compromise the flexibility and comfort of the sole, particularly in the heel.
Although different constructions exist that provide either durability or flexibility and comfort, there are few footwear that provide both.